Lubricant including a molybdenum-containing organic material



res i tnt ice 3,047,500 LUBRICANT INCLUDENG A MOLYBDENUM- CONTAINING ORGANIC MATERIAL Howard J. Matson, Harvey, Ill., assignor, by mesne assignments, to Sinclair Research, Inc, New York, N.Y.,

a corporation of Delaware No Drawing. Filed Apr. 4, 1958, Ser. No. 726,321

13 Claims. (Cl. 252-417) The present invention is directed to novel organomolybdenum compounds and to lubricants which contain them and which may contain them in combination with other additives.

The increases in gear and bearing loading within recent years, and more rigorous service conditions in other instances of metal-to-metal contact, have made extreme pressure lubricants and lubrication a limiting factor in performance. It is well known to those familiar with the art that alubricating oil such as a mere refined petroleum oil fraction is incapable of maintaining a lubricating film between engaged metallic surfaces where the unit load at the engaged surfaces exceeds a pressure of say 3,000 to 4,000 pounds per square inch. In various types of modern machinery, such as the hypoid gears used in motor vehicles, the engaging pressures between the gear teeth are so high that ordinary lubricating oils alone are incapable of properly lubricating them, the abnormally high pressures generally causing serious rupture of the oil film. To overcome this problem, special extreme pressure type lubricants have been developed. These lubricants are prepared by incorporating into a petroleum lubricating oil, or other suitable carrying agent, an additive ingredient which will form a lubricant film capable of withstanding these abnormally high pressures.

Ingredients of this character are known as extreme pressure (E:P.) ingredients. In addition, the American Petroleum Institute has adopted the designation Multipurpose-Type Gear Lubricant (A.P.I. Service GL-4) to define gear lubricants that are compounded with higher performance additives which provide an advanced E.P. lubricant. Such a lubricant has an improved load carrying ability and other properties to protect hypoid gears in sustained high speed and/or high torque service.

This, invention provides an 'ElP. type lubricant which excels known lubricants in certain respects, and in a preferred embodiment, excels known lubricants in passing most standard E.P. type lubricant tests. The lubricant contains a novel oil-soluble molybdenum compound and in addition, a preferred embodiment also contains an oilsoluble organic sulfur compound. It is hypothesized that in the preferred embodiment the two additives react, under extreme pressure conditions, to form a protective MOSZ film on metal surfaces.

The good lubricating properties of molybdenum disulfide films are well known. These films have a low coefficient of friction andsurvive to protect metal surfaces under extreme pressure conditions. It is believed that the lubricating properties of M05 are based on its laminar structure, where each lamina is composed of a layer of molybdenum atoms contained between two layers of sulfur atoms. The attractive forces in a single lamina, and between a single lamina and a metal surface, are relatively high due to the strength of the metal-to-s'ulfur bond. However, the attractive forces between separate laminae are relatively low, due to the weakness of the sulfur-to-sulfur bond. Separate laminae will therefore tend .o slide over each other, but will adhere tenaciously to metal surfaces.

Because M05 films are chemically inert and thermally .oils whether or not sulfur is available in the oil.

a solid and uniform bond with the metal surface. A bonded M03 film may be formed by hard mechanical rubbing, or by baking in the presence of a binder such as corn syrup. 'In contrast with the good E.'P. properties of a bonded M08 film, M08 itself is not an effective extreme pressure additive for lubricating oils. A basic difficulty is its insolubility in natural and synthetic lubricating fiuids, causing it to eventually separate and settle in storage. Although M08 can be dispersed to some extent in lubricating oils, both mechanically and with dispersing agents, such dispersions do not approach bonded MoS film properties.

The novel molybdenum compounds of this invention have been found to give E.P. characteristics to lubricating The novel molybdenum compound is the oil-soluble reaction product of molybdenum pentachloride and an oil-soluble alkyl phenol, for instance a polyalkyl or dialkyl phenol containing a total of at least 6 carbon atoms in the side chains. No chain of the phenol reactant will usually contain more than 18 carbon atoms and the total number of carbon atoms in the chains will ordinarily not be more than 24.

The reaction product which contains molybdenum trichloride alkyl phenolate can be manufactured by heating a mixture of the molybdenum pentachloride and phenol while removing HCl. The ingredients are preferably reacted while dissolved in a mutual solvent, such as toluene or xylene, under refluxing conditions of temperature and pressure.

The major product of this reaction is the triphenolate, although minor amounts of the mono-, di-, or tetraphe nolate may be present in the reaction product. The compound and scheme for the reaction of molybdenum pentachloride and diamyl phenol is as follows:

The triphenolate need not be separated from the other molybdenum phenolates of the reaction product for blending with an oleaginous liquid lubricating base.

The reaction product of molybdenum pentachloride and diamyl phenol is particularly preferred as the ER additive of this invention because of its solubility in the lubricant base and its ease of manufacture from readily available materials. The theory analysis of molybdenum chloride tri (diamyl) phenolate is molybdenum, 11.1 percent;chlorine, 8.2 percent.

The lubricating oil suitable for blending with the novel molybdenum compound of this invention can be a mineral lubricating oil fraction of the conventionally refined or solvent refined type. The mineral lubricating oil fraction can be derived from a parafiinic, naphthenic or Mid- Continent crude and is of lubricating viscosity, e.g. from about 50 SUS at F. to 200 SUS at 210 F. The

use ofa low viscosity non-naphthenic 100 percent solvent refined neutral Mid-Continent base lubricating oil provides an E.P. lubricant .having better low temperature pumpability. A blend of naphthenic and solvent refined Mid-Continent lubricating oil bases may also be used with advantage.

In addition to the distillate mineral lubricating oils mentioned, the various types of synthetic liquid oleaginous lubricating bases having comparable viscosities can also be employed as part or all of the lubricating base with the additive of this invention. Among the types of synthetic liquid oleaginous lubricating bases which can be employed are the oil-soluble high boiling high molecular weight aliphatic ethers, aromatic esters, aliphatic monoand dicarboxylic esters, phosphorus acid esters and halogenated aromatic compounds which possess lubricating properties and also have small change in viscosity for a aoeveoo given change in temperature. Of the various synthetic oleaginous compounds specified, those falling within the category of aliphatic dicarboxylic acid esters, and particularly the branched chain aliphatic diesters, such as di- 2-ethylhexyl sebacate, are preferred.

The molybdenum phenolate is blended with the lubricant base in proportions sufficient to give E.P. characteristics, usually about 0.1 to 10, preferably about 1 to 5 percent of phenolate in the final blend.

As has been mentioned, it has also been found that a lubricant composition containing available sulfur provides an additionally valuable E.P. lubricant. Sulfur is easily made available by blending with the lubricant base certain oil-soluble organic sulfur compounds. These compounds usually contain 6 to 30 carbon atoms, preferably 8 to 18 carbon atoms, in the molecule. The compounds which are preferred are sulfurized fatty oils such as sulfurized sperm oil, sulfurized rape seed oil, sulfurized cotton seed oil and sulfurized palm oil. Sulfurized olefins, such as a polyisobutylene or mixture of diand triisobutylenes which has been subjected to treatment first with sulfuryl chloride and then with sodium polysulfide, are also satisfactory for use with the novel E.P. ingredient another machine, even though both machines are recognized as extreme pressure lubricant testers. In view of the well-known hazards in trying to extrapolate E.P. performance in a single laboratory tester to performance under field service conditions, this versatile performance demonstrates a good probability of successful usage in a variety of practical applications.

The varied laboratory E.P. tests referred to were made on 2 Wt. percent blends of the additive contained in a 95 V1. solvent refined neutral mineral lubricating oil of about 33 SUS viscosity at 100 F.

The performance of the novel additive of the invention was compared with the performance of a standard additive which has been given a GL-4 rating. Details of the 4-Ball test can be found in Boerlage, Four-Ball Testing Apparatus for Extreme Pressure Lubricants, 136, Engineering, p. 46 (1933). The SAE test is described in the Journal of the Society of Automotive Engineers, July 1936, p. 293. The Falex breakdown test is described in Lubrication Engineering, Sept. 1946, pp. 1-9. Details of the Timken L-20 weedout test can be found in the US. Patent No. 2,715,612.

The results of these tests are given in Table I.

TABLE I Sample I Additive (Wt. percent) Molybedenum Phenolate of E Sulfurized sperm oil (12% S) High performance GL-4 type multipurpose gear oil additive ampl i -Ball E.P. Test- Weld, Kg 158 178 355 251 141 Mean Hertz Load 13. 7 42.0 75.1 33. 5 33.4 Falex Breakdown Test, lbs 300 4, 500+ 4, 500+ 2, 500 3,000 SAE load at 300 rpm, lbs (Falls 237 500+ 136 307 Timken Test during Wear (mg) break- 36.0 16.0 32.0 32. 5 Condition of cup and block in) lines polish polish linets- 1 100 lbs. at 200 rpm. and 200 F. for 16 hours.

of the invention. One such sulfurized olefin contains up to 46 percent sulfur by weight. A particularly efiective material is sulfurized sperm oil which contains about 5 to 15 weight percent of combined sulfur. This additive can be employed in effective amounts of about 0.3 to 5 percent to contribute about 0.06 to 0.2 percent by weight of sulfur on the basis of the oleaginous liquid lubricant base of the composition. In general, the sulfur compound is used in the ranges of amounts indicated for the molybdenum phenolate. The compositions of this invention can contain other additive agents such as pour depressors, anti-foam agents and viscosity index improvers.

The following example illustrates the preparation of the organic molybdenum reaction product: 46 gm. (0.168 mole) of MoCl were refluxed in 250 ml. toluene to dehydrate and remove occluded Water. 117 gm. of diamyl phenol (0.5 mole) (Sharples, OH value=240) in 300 ml. of toluene were similarly dehydrated. After cooling to about 60 C. the MoCl -toluene mixture was combined with the diamyl phenol solution and the reaction mixture refluxed for a total of eleven hours, or until there was no further evolution of HCl gas. The reaction mixture was then filtered to remove some sludge and unreacted solids, and the bulk of the solvent was removed by distillation to 115 C. pot temperature at about 15 mm. mercury pressure. The product, which was estimated to contain about 10 percent residual solvent, gave the following analysis: molybdenum, 7.94%; chlorine, 4.14%. The product is a liquid of intense blue-violet color.

The effectiveness of this compound as an extreme pressure additive can be demonstrated in a variety of laboratory E.P. test machines. This in itself is unusual because frequently an additive which is shown to be advantageous by one machine is not shown to be similarly effective by These tests clearly demonstrate superior extreme pressure lubricant properties for the molybdenum phenolate containing blend, especially when in combination with an organic compound containing available or reactive sulfur. The latter composition permits .a maximum load limit in both the SAE and Falex lubricant testers. Performance in the 4-ball test, which is frequently cited to demonstrate E1. properties, is particularly outstanding. The Timken test shows that E.P. performance is obtained without any sacrifice of wear properties.

It is reasonable to theorize that the lubrication provided by this composition used in conjunction with a sulfur-containing additive is a result of a reaction between the sulfur and molybdenum additives, to form in situ a film of M08 on the worked surfaces. At the very least, the blend containing both sulfur and molybdenum combines the best characteristics of the separate blends,- and in the case of the wear test, shows less wear than either of the individual additive blends.

Regardless of the mechanism, however, it is readily apparent from the data given in Table I that a molybdenum phenolate, blended alone or with an oil-soluble organic sulfur compound, provides an unusually effective E.P.' composition. The degree of this improvement is indicated by comparison with the performance of other high performance multipurpose type gear oil additives, which are recommended for use in both high torque and high speed operation.

I claim:

1. A lubricant consisting essentially of an oleaginous liquid lubricating base oil and a sufficient amount of an oil-soluble molybdenum dichloride tri (alkyl) phenolate to impart extreme pressure characteristics to the lubricat- 3. The lubricant composition of claim 1 in Which the lubricating base oil is a mineral lubricating oil.

4. The lubricant composition of claim 1 in which the molybdenum phenolate is about 0.1 to of the composition.

5. The lubricant composition of claim 2 in which the lubricating base oil is a mineral lubricating oil.

6. The lubricant composition of claim 4 in which the lubricating base oil is a mineral lubricating oil.

7. The lubricant composition of claim 6 which contains an oil-soluble organic sulfur compound containing 6 to 30 carbon atoms and having available sulfur, in a minor .amount to provide a further improvement in extreme pressure chaarcteristics.

8. The lubricant composition of claim 7 in which the oil-soluble organic sulfur compound is about 0.3 to 5 percent of the composition to provide about 0.06 to 0.2 percent by weight of sulfur based on the lubricating oil.

9. The lubricant composition of claim 8 which contains about 1 to 5 weight percent of an oil-soluble sulfurized fatty oil.

10. The lubricant composition of claim 9 in which the sulfurized fatty oil is sulfurized sperm oil containing about 5 to 15 weight percent of combined sulfur.

11. A lubricant consisting essentially of a mineral lubricating base oil and about 1 to 5 weight percent of oil-soluble molybdenum dichloride tri (dialkyl) phenolate, said alkyl portion of the phenolate groups containing a total of 6 to 24 carbon atoms.

12. The lubricant composition of claim 11 which contains about 1 to 5 weight percent of an oil-soluble sulfurized fatty oil having available sulfur, said sulfurized fatty oil being present in a minor amount to provide a further improvement in extreme pressure characteristics.

13. The lubricant composition of claim 12 in which the sulfurized fatty oil is sulfurized sperm oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,507 Roehner et al. June 4, 1940 2,402,448 Richards June 18, 1946 2,518,379 Rogers et a1. Aug. 8, 1950 2,619,459 Neff Nov. 25, 1952 2,818,416 Brown et al Dec. 31, 1957 FOREIGN PATENTS 556,797 Germany Aug. 17, 193-2 

1. A LUBRICATING CONSISTING ESSENTIALLY OF AN OLEAGINOUS LIQUID LUBRICATING BASE OIL AND A SUFFICIENT AMOUNT OF AN OIL-SOLUBLE MOLYBDENUM DICHLORIDE TRI (ALKYL) PHENOLATE TO IMPART EXTREME PRESSURE CHARACTERISTICS TO THE LUBRICATING BASE OIL, SAID ALKYL PORTION OF THE PHENOLATE GROUPS CONTAINING A TOTAL OF 6 TO 24 CARBON ATOMS. 